Uncommon 1,2-Migration of a Nitro Group Within a β-Nitrostyryl Moiety: Synthetic Scope and Mechanistic Details

The unusual migration of a nitro group from the - to the -position of a -aryl--nitroethenyl moiety, following a nitrocyclopropane to isoxazoline N-oxide isomerization, has been studied from a mechanistic and synthetic points of view. As a result, two series of isomeric isoxazoline N-oxides could be obtained under controlled conditions. When reacted with diazomethane, a model transposed isoxazoline cleanly furnished a new, interesting pyrazolylisoxazole.